India’s first
indigenously designed
and developed High
Thrust cryogenic rocket
engine generating a
nominal thrust of 19
tonnes was successfully
endurance hot tested for
a duration of 800
seconds on July 16, 2015
at ISRO Propulsion
Complex, Mahendragiri.
This duration is
approximately 25% more
than the engine burn
duration in flight. The
engine will be used for
powering the Cryogenic
stage (C25), the upper
stage of the next
generation GSLV Mk-III
launch vehicle of ISRO,
capable of launching
four tonne class
satellites.

This high performance
cryogenic engine was
conceived, configured
and realised by Liquid
Propulsion Systems
Centre (LPSC), the lead
centre of Indian Space
Research Organisation
(ISRO) responsible for
developing liquid
propulsion systems for
Indian Space Programme.
The Engine design was
totally in-house effort
with experts from
different fields like
fluid dynamics,
combustion, thermal,
structural, metallurgy,
fabrication, rotor
dynamics, control
components, etc.,
working together. The
fabrication of major
subsystems of the engine
was carried out through
Indian Industries.
Assembly and Integration
of the engine and
Testing were carried out
in ISRO Propulsion
Complex (IPRC), a unit
of ISRO.

LPSC has also developed
a cryogenic upper stage
of 12.5 tonne propellant
loading and successfully
flight tested it in GSLV
Mk-II vehicle on January
05, 2014. Compared to
this stage, the C25
stage has a higher
propellant loading (27
tonnes versus 12.5
tonnes) and higher
engine thrust (19 tonne
versus 7.5 tonne). The
recent successful
endurance hot test of
the first high thrust
cryogenic engine is the
tenth test in a series
of tests planned and
executed as part of the
development of the
engine employing complex
cryogenic technology.
The performance of the
engine closely matches
with the pre-test
prediction made using
the in-house developed
cryogenic engine
mathematical modelling
and simulation software.
Prior to engine
realisation, a series of
subsystem level tests
were carried out to
independently evaluate
the design of major
subsystems like the
turbopumps, thrust
chamber, gas generator,
flow control components,
etc. Based on the
confidence gained, the
integrated engine
testing was initiated.
As part of the C25 Stage
development, further
tests are planned in
High Altitude conditions
and in Stage
configuration, prior to
the flight stage
realisation. Mastering
this complex, high
performance cryogenic
propulsion technology
will go a long way in
building self reliance
for the Indian Space
Programme.